"The mission calls for these atrocities to be fully investigated and for the perpetrators and their commanders to be held accountable," he said.

Reminding the parties to the conflict of their obligation to protect civilians, Dujarric said the mission "calls on them to immediately cease targeting unarmed civilians and respect the cessation of hostilities agreement signed in January."

The latest massacre was one of the worst since fighting erupted within the military on December 15 between troops loyal to President Salva Kiir and those backing Machar.

It then spread to the rest of the country, accompanied by numerous atrocities against civilians.

The fighting, which has already left several thousand dead, has taken on ethnic dimension with roots in long-held hostilities between the Dinka and Nuer people, respectively represented by Kiir and Machar.